• Nuclear Engineering and Technology
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• 제38권3호
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• pp.225-230
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• 2006

With the advent of inexpensive computing power over the past two decades, applications of Monte Carlo radiation transport techniques have proliferated dramatically. At Los Alamos, the Monte Carlo codes MCNP5 and MCNPX are used routinely on personal computer platforms for radiation shielding analysis and dosimetry calculations. These codes feature a rich palette of variance reduction (VR) techniques. The motivation of VR is to exchange user efficiency for computational efficiency. It has been said that a few hours of user time often reduces computational time by several orders of magnitude. Unfortunately, user time can stretch into the many hours as most VR techniques require significant user experience and intervention for proper optimization. It is the purpose of this paper to outline VR strategies, tested in practice, optimized for several common radiation shielding tasks, with the hope of reducing user setup time for similar problems. A strategy is defined in this context to mean a collection of MCNP radiation transport physics options and VR techniques that work synergistically to optimize a particular shielding task. Examples are offered in the areas of source definition, skyshine, streaming, and transmission.

• 방사선산업학회지
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• 제17권4호
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• pp.451-456
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• 2023

The subject of this research is what is the most effective strategy of the nuclear sharing strategy of South Korea through the nuclear strategy that the U.S. is pursuing now. The U.S. Nuclear Strategy-related change can be found in a Nuclear Posture Review (NPR) report released by the U.S. The first NPR was announced in 1994 and after that, the U.S. has additionally announced a total of four NPRs along with administration changes. The change in the U.S. nuclear strategy and nuclear power are considered both deterrence and offset strategies. It can be summarized in two ways. First, by maintaining overwhelming nuclear power against the enemy, the U.S. is to lead nuclear advantage that is the core of the U.S. nuclear strategy. Second, the U.S. is to limit the competition of nuclear power with nations seeking to challenge the U.S. nuclear power advantage. Additionally, the U.S. is to actively sign an agreement with nations on the reduction and restriction of nuclear weapons. Through the NPR of the U.S., South Korea should know its unclear power and strategy and have an effective nuclear strategy of South Korea. Therefore, this research is to deal with the suitability of the nuclear sharing strategy with the U.S., which is one of the various nuclear strategies of South Korea.

• 한국환경복원기술학회지
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• 제21권6호
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• pp.1-13
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• 2018

Mapping radiation heat flux of urban area is essential for urban design and landscape planning. Because controlling urban geometry and generating green space are important urban design strategies for reducing urban heat, urban planner and designer need to recognize the micro urban heat distribution for adequate urban planning. This study suggests a new methodology for mapping urban radiation heat flux in a micro scale considering buildings and trees' shade. For doing that, firstly, we calculate net radiation for each urban surfaces (building, road (not shaded, building shaded, tree shaded), ground (not shaded, building shaded, tree shaded), tree (not shaded, building shaded)). Then, by multiplying the area ratio of surfaces to the net radiation, we can obtain the radiation heat flux in micro-scale. The estimated net radiation results were found to be robust with a $R^2$ of 90%, which indicates a strong explanatory power of the model. The radiation heat flux map for 12h $17^{th}$ August explains that areas under the building and tree have lower net radiation heat flux, indicating that shading is a good strategy for reducing incident radiation. This method can be used for developing thermal friendly urban plan.

• Journal of Radiation Protection and Research
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• 제34권3호
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• pp.95-101
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• 2009

Protective behavior of radiological technologists against radiation exposure is important to achieve reduction of the patient doses without compromising medical achievements. This study attempts to provide a basic model for the sophisticated intervention strategy that increases the level of the protective behavior of the technologists. The model was applied to real situations in Korea to demonstrate its utility. The results of this study are summarized as follows: First, the protective environment showed the highest relationship in the factors considered, r=0.637 (p<0.01). Secondly, the important factors were protective environment in environment characteristics, expectation for the protective behavior 0.228 (p<0.001), self-efficacy 0.142 (p<0.001), and attitude for the protective behavior 0.178 (p<0.001) in personal characteristics, and daily patient -0.112 (p<0.001) and number of the participation in the education session for the protective behavior 0.074 (p<0.05). Thirdly, the final protective behavior model by a path analysis method had direct influence on the attitude 0.171 (p<0.01) and environment 0.405 (p<0.01) for the protective behavior, self efficacy 0.122 (p<0.01), expectation for the protective behavior 0.16 (p<0.01), and self-efficacy in the specialty of projects 0.154 (p<0.01). The acceptance of the model determined by the absolute fit index (GFI), 0.969, and by the incremental fit index (CFI), 0.943, showed very significant levels. Value of $x^2$/df that is a factor applied to verify the acceptance of the model was 37, which implies that the result can be accepted in the desirable range. In addition, the parsimonious fit index configured by AGFI (0.890) and TLI (0.852) was also considered as a scale that accepts the model in practical applications. In case of the establishment of some specific intervention strategies based on the protective behavior model against harmful radiation effects proposed in this study, the strategy will provide an effective way to prevent medical harmful radiation effects that could cause severe injuries to people.

• 대한두경부종양학회지
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• 제38권2호
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• pp.7-13
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• 2022

Human papillomavirus (HPV) is a causative agent for a subset of oropharyngeal cancer (OPC). The current standard of care (SOC) for locally advanced OPC is 70 Gy definitive radiotherapy (RT) concurrent with cisplatin, which entails significant proportions of acute and late grade 3 or higher toxicities. Accordingly, discovery of favorable prognosis of HPV-related OPC has led to enthusiasm to attenuate subspecialties therapy in multidisciplinary treatment. Diverse deintensification strategies were investigated in multiple phase 2 trials with an assumption that attenuated treatments result in comparable oncologic outcome and less toxicities compared with SOC. Several trials on chemotherapy deintensification revealed that concomitant administration of cisplatin is not to be omitted or substituted for cetuximab without compromising progression-free survival or local control. A transoral robotic surgery (TORS) is investigated as alternative local treatment, but TORS plus SOC or mild deintensified adjuvant RT showed similar toxicities and inferior oncologic outcomes compared with SOC definitive RT or moderately deintensified RT. However, it has been reported that TORS plus deintensified 30-36 Gy adjuvant RT results in excellent outcome and less late toxicity compared with SOC adjuvant RT. Several phase 2 trials reported apparently equivalent progression-free survival and local control and similar adverse effects with moderately deintensified 60 Gy RT compared with SOC 70 Gy RT. Further dose reduction below 60 Gy has been investigated using biology-directed approaches, which use response to induction chemotherapy or metabolic images to triage HPV-positive OPC for deintensified RT. In summary, these trials provide valuable insights for future directions. Available evidence consistently showed that moderately deintensified RT is effective and safe for HPV-positive OPC in both definitive and adjuvant settings. Concurrent cisplatin remains an essential component without which progression-free survival is significantly compromised for advanced HPV-positive OPC. A simple incorporation of TORS to SOC may be detrimental for oncologic outcome without anticipated toxicity reduction. Given the lack of level 1 evidence, it is prudent to curb an unjustified deviation from the current SOC and limit any deintensified strategies to clinical trials and adhere to the current SOC.

• ETRI Journal
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• 제40권6호
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• pp.699-713
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• 2018

Orthogonal frequency division multiplexing (OFDM) has been the overwhelmingly prevalent choice for high-data-rate systems due to its superior advantages compared with other modulation techniques. In contrast, a high peak-to-average-power ratio (PAPR) is considered the fundamental obstacle in OFDM systems since it drives the system to suffer from in-band distortion and out-of-band radiation. The partial transmit sequence (PTS) technique is viewed as one of several strategies that have been suggested to diminish the high PAPR trend. The PTS relies upon dividing an input data sequence into a number of subblocks. Hence, three common types of the subblock segmentation methods have been adopted - interleaving (IL-PTS), adjacent (Ad-PTS), and pseudorandom (PR-PTS). In this study, a new type of subblock division scheme is proposed to improve the PAPR reduction capacity with a low computational complexity. The results indicate that the proposed scheme can enhance the PAPR reduction performance better than the IL-PTS and Ad-PTS schemes. Additionally, the computational complexity of the proposed scheme is lower than that of the PR-PTS and Ad-PTS schemes.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.187-195
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• 2011

Glass Envelope is vulnerable to insulation performance and controling solar radiation. Insulation performance is consistently improving these days due to recent building energy saving policy in South Korea. However, solar control at glass envelope is still limited to meeting requirements of ideal high performance. Generally, Inside Blind plays an important role of solar control instead of glass which have a characteristics of transmitted solar. Unfortunately, most of them are controled by occupants and which method is not resonable in building energy. Therefore, achieving the high efficient performance building, automated control blind system considering reduction of building loads have to be adopted. Furthermore, considering occupants visual comport about removing discomfort glare is also essential.

• 한국의학물리학회지:의학물리
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• 제19권4호
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• pp.276-284
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• 2008

전 세계적으로 컴퓨터 단층 촬영 장치(Computed Tomography, CT)의 임상 적용이 환자의 질병의 조기 진단에 매우 중요하게 사용되고 있으며 사용 빈도 또한 매년 급증하고 있다. 새로운 종류의 CT 장치들이 병변을 조기 진단하기 위하여 개발되고 있다. 이 방사선 발생 장치에 의한 환자나 작업 종사자들의 방사선 피폭이 불가피 할 수도 있다. 국내에서는 CT 장치에 대한 구체적인 방사선 방어나 방사선 시설에 대한 구체적인 규정이 확립되어 있지 않다. 본 논문에서는 국내에서의 CT 사용시설에 대한 방사선 방어 시설과 사용 기준에 대한 규정 마련에 토대를 이루기 위하여 외국에서의 CT 장비에 대한 방사선 방어 및 방사선 차폐에 대한 규정을 조사하였다. 조사방법으로는 구글 검색을 이용한 특정 키워드 검색과 방사선 관련 업무를 수행하는 특정 웹사이트를 직접 검색하는 방법을 사용하였다. 검색결과 캐나다, 미국, 영국 등의 국가에서 국가의 실정에 맞는 가이드라인을 사용하고 있었으나, 아직 이중 에너지 CT에 대한 가이드라인은 없는 것으로 나타났다. 한국에서도 국내 실정에 적합한 CT 장비에서의 방사선 방어, 차폐, 환자나 작업종사자 및 일반인에 대한 방사선 피폭에 대한 가이드라인의 설정이 필요하다고 생각된다.

• 한국방사선학회논문지
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• 제18권3호
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• pp.283-292
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• 2024

안와림프종의 전자선 치료 시 안구 부속기관의 방사선 부작용 및 합병증으로 인해 후낭하백내장 발생률이 높아질 수 있다. 이에 본 연구는 몬테카를로 전산모사를 활용하여 의료용 선형가속기와 안구의 수학적 모델을 모사하고, 안구 부속기관에 대한 선량평가와 수정체 차폐체 두께에 따른 안구 부속기관별 차폐율을 비교 분석하였다. 안구 부속기관의 선량평가 결과, 차폐체 미사용 시 선량을 기준으로 수정체의 민감 영역에서 가장 높은 흡수선량 분포를 보였으며, 그 외 수정체의 비민감 영역, 전방, 유리체, 각막, 눈꺼풀 순으로 점차 낮아지는 경향을 나타내었다. 차폐체 사용 시 선량 분석 결과, 2 mm 두께 사용 시 수정체의 민감 영역에서 90% 이상의 선량감소효과를 나타냈으며, 비민감 영역과 전방은 83% 이상, 유리체, 각막, 눈꺼풀에서는 30 ~ 62%의 선량감소효과를 보였다. 안와림프종의 전자선 치료 시 수정체 민감 영역의 선량 저감을 위해서는 최소 2 mm 이상의 차폐체 사용이 필요할 것으로 판단되며, 수정체 이외 안구 부속기관에 대한 차폐체 두께 및 면적을 고려한 차폐 방안이 필요할 것으로 사료된다.

• Journal of Radiation Protection and Research
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• 제28권3호
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• pp.189-197
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• 2003

Level 3 PSA(사고결말분석)는 원자력 발전소의 사고 시 누출된 방사성 핵종으로 인해 야기되는 환경 및 인체에 미치는 영향(공중위험도)을 평가하는 것이다. 본 논문에서는 원자력 발전소의 중대사고시 환경으로 방출되는 방사성물질의 방출특성과 그 결과로 인체에 미치는 영향에 대하여 확률론적 사고영향분석코드인 MACCS를 이용하여 평가하였다. 이러한 평가는 관련 변수들의 상대적 중요도를 파악하는데 유용할 뿐만 아니라 소외리스크(Offsite Risk)를 최소화시키기 위한 대책개발에 있어 중요한 지표가 될 수 있다. 특히 방출고도, 열 함량, 방출기간의 3가지 중요 변수를 선정하여, 이들 변수들의 변화에 따라 영향을 받는 조기사망자 수와 암 사망자 수의 변화를 분석하였다. 또한, 참조원전의 위험성 평가를 위하여 IPE(Individual Plant Examination)에서 제시된 STC(Source Term Category) 19가지 시나리오에 대한 각 사고별 빈도와 MACCS코드를 수행한 결과값을 이용하여 참조원전의 위험성 평가를 수행하였다.